The invention relates in general to communication systems and more specifically to an apparatus, system, and method for managing reverse link (uplink) communications in a communication system.
Many wireless communication systems employ geographically distributed base stations to provide communication cells or regions where a serving base station provides communication service to mobile stations within the region corresponding to the serving base station. In certain situations, the reverse link signals transmitted from each mobile station to a base station interfere with other reverse link signals transmitted from other mobile stations. Because of the interference and limited resources, the capacity of each base station is limited. A reverse link capacity of a base station is affected by the reverse link load due to the mobile stations served by the base station, by the coupled reverse link load due to mobile stations served by other base stations and by other noise sources. Reverse link load scheduling provides a mechanism for maximizing efficient use of system resources by controlling the transmissions of mobile stations. In conventional communication systems, a centralized controller evaluates the reverse link load and the reverse link coupled load, as well as other factors, to determine the appropriate load scheduling. For most data applications, however, mobile stations are controlled by a single serving base station to reduce scheduling delays although the reverse link transmissions can affect the load at other base stations.
Conventional systems, however, are limited in several ways. For example, the communications with the centralized controller result in significant delays. Information gathered by each base station is forwarded to the centralized controller. The centralized controller processes the information, determines an optimum load capacity for each base station, and sends the optimum load capacity to each of the base stations. Each base station limits the communications of the mobile stations that it is serving in accordance with the updated load capacity provided by the controller. The channel conditions, however, often change during the time that is required to transmit, process, and receive the optimum load capacity. Accordingly, a base station may be operating at a level significantly different from the optimum level resulting in unused resources or an overload condition. An overload condition may occur, for example, where a base station operating in accordance with the latest optimum capacity information that was provided by the controller may overload another base station that is attempting to operate near its maximum capacity because delays in the system have not allowed the new channel conditions to be reflected in the information conveyed to the base stations. Overload conditions lead to lost data, re-transmissions of messages, and other undesired consequences.
Accordingly, there is need for an apparatus, system, and method for efficiently allocating reverse channel resources in a communication system with geographically distributed base stations.